This invention relates to splices for belts and, more particularly, to mechanical splices for high tension belts.
Several types of splices have been used in the past for splicing the ends of belts which are used in high tension applications such as in bucket elevators. Some belt manufacturers suggest that the ends of the belt be lapped over each other and bolted together with several bolts. The bolts are expected to take the shear stress which occurs when the ends of the belt try to slide parallel to each other due to the tension on the belt. This type of splice has been found to be unsatisfactory in some bucket elevator applications, because, when a bucket is bolted onto the spliced area of the belt, the bolts holding the bucket on tend to fail. The failure is probably due to the relative movement of the two lapped belt ends in the splice which take unequal loads when passing over the pulley.
In other splices, the ends of the belt have been curved at approximately right angles to the rest of the belt. Plates are put on the outside of the belt ends, and the plates are bolted together, clamping the belt ends between the plates. With this kind of a splice, instead of strictly a shear force on the bolts, a large portion of the force on the bolts is a tension force, in a direction perpendicular to the plates, caused when the ends of the belt try to pull apart. The remainder of the force is in a direction parallel to the plates, again trying to shear the bolts. In these arrangements, part of the force parallel to the plates is handled by friction of the plates clamping the belts, and in some cases the inside of the plates is roughened or toothed to help grip the belts. This arrangement avoids the problem of buckets falling off, because the buckets no longer are bolted through an area in which there is a double thickness of belts. However, this splice tends to fail due to fatigue failure of the bolts, because the tension on the bolts repeatedly changes as buckets are loaded and dumped, as the splice passes over pulleys, and so forth. The bolts in this arrangement cannot be pretensioned to a high tension, due to the "give" in the belting material.
A main object of the present invention is to provide a splice for high tension belts which lasts longer than the splices which are presently available. Another object of the present invention is to provide a splice for high tension belts in which the bolts holding the splice together can be pretensioned, so that repeatedly changing the loading on the belts does not tend to cause fatigue in the bolts holding the splice together. Another object of the present invention is to provide a belt splice which avoids the problems involved in attaching buckets through two thicknesses of belts.